1202.4492 (M. P. M. Dean et al.)

Observation of magnetically polarized Ir dopant atoms in superconducting
Ba(Fe$_{1-x}$Ir$_x$)$_2$As$_2$    [PDF]

M. P. M. Dean, M. G. Kim, A. Kreyssig, J. W. Kim, X. Liu, P. J. Ryan, A. Thaler, S. L. Bud'ko, W. Strassheim, P. C. Canfield, J. P. Hill, A. I. Goldman

We investigate the magnetic polarization of the Ir $5d$ dopant states in the
pnictide superconductor Ba(Fe$_{1-x}$Ir$_x$)$_2$As$_2$ with $x=0.027(2)$ using
Ir $L_3$ edge x-ray resonant magnetic scattering (XRMS). Despite the fact that
doping acts to suppress the antiferromagnetic transition, we find that magnetic
order survives around the Ir dopants sites. The Ir states are magnetically
polarized with commensurate stripe-like antiferromagnetic order and long
correlations lengths, $\xi_{\text{mag}}>$ 2800 and 850 \AA{}, in the $ab$-plane
and along the c-axis, respectively, driven by their interaction with the Fe
spins. This Ir magnetic order coexists with superconductivity at 5 K and
persists up to the N\'{e}el transition of the majority Fe spins at $T_N=74(2)$
K. The energy dependence of the XRMS through the Ir $L_3$ edge shows a
non-Lorentzian lineshape, which we explain in terms of interference between Ir
resonant scattering and Fe non-resonant magnetic scattering.

View original: http://arxiv.org/abs/1202.4492